Electrical heating unit

ABSTRACT

The present invention relates generally to improvements in electrical heating units, and more particularly to improvements in electrical heating units of the type employing wafer-like material or sheets such as mica having an electrical heating coil associated therewith. The embodiment of the invention disclosed herein includes thin coplanar sheets of heat resistant, electrically non-conductive material such as mica, the outer peripheries of which in the aggregate generally define a circle. Diametral margins of said sheets are adjacently spaced and an electrical heating coil adjacently encircles said sheets. A terminal member is connected with each extremity of the coil, and suitable electrical insulating material adjacently superimposes opposite sides of the sheets. Means is provided for maintaining the sheets and insulating material in juxtaposition.

United States Patent n91 Hummel 1 3,714,395 145] Jan. 30, 1973 [73]Assignee: Acra Electric Corporation, Schiller Park,lll.

[22] Filed: Jan. 14, 1971 [21] Appl. No.: 106,325

[52] U.S. Cl. ..2l9/544, 219/432, 219/433, 219/552, 338/301 [51] Int.Cl. ..H05b 3/44, 1105b 3/50 [58] Field of Search ..2l9/432, 433, 430,436, 438, 219/345, 464, 458, 457, 544,218, 536, 552; 338/218, 286-288,301, 299

[56] References Cited UNITED STATES PATENTS 957,226 5/1910 Logan..338/30l X 1,170,169 2/1916 Kuhn et a1. ..2l9/433 X 2,448,388 8/1948Plummer ..219/433 1,153,703 9/1915 Phelps ..338/301X 1,484,280 2/1924Spahr ..338/30l X 2,568,465 9/1951 Scott ..338/2l8 X 2,570,975 9/1951Osterheld ..219/462 X 2,605,382 7/1952 Kircher et a1 ..2l9/433 2,272,4712/1942 Miller ..219/436 FOREIGN PATENTS OR APPLICATIONS 1,129,244 5/1962Germany ..338/30l Primary ExaminerVolodymyr Y. Mayewsky Attorney-Olson,Trexler, Wolters & Bushnell 5 71 9 ABSTRACT The present inventionrelates generally to improvements in electrical heating units, and moreparticularly to improvements in electrical heating units of the typeemploying wafer-like material or sheets such as mica having anelectrical heating coil associated therewith. The embodiment of theinvention disclosed herein includes thin coplanar sheets of heatresistant, electrically non-conductive material such as mica, the outerperipheries of which in the aggregategenerally define a circle.Diametral margins of said sheets are adjacently spaced and an electricalheating coil adjacently encircles said sheets. A terminal member isconnected with each extremity of the coil, and suitable electricalinsulating material adjacently superimposes opposite sides of thesheets. Means is provided for maintaining the sheets and insulatingmaterial in juxtaposition.

1 Claim,.5 Drawing Figures Italy ..2l9/438 ELECTRICAL HEATING UNITSUMMARY OF THE INVENTION One of the problems incident to the use ofcommercially available heating units such as heating units in the formof coils set in ceramic material, or heating elements enclosed within aceramic tube, is that of maintaining uniform heat delivery to a hotplate or disc.

Another problem encountered when conventional heating units are employedin association with the hot plate for coffee containers and the like, isthat of encountering short circuiting which results from heated liquidentering the area below the hot plate and contacting the heating coil.

It is an important object of the present invention to provide a compact,disc-like heating unit, which because of its structural design, willassure uniform heat delivery and which will preclude the above-mentionedproblem of short circuiting.

Another object of the present invention is to provide the heating unitof the type set forth above which readily lends itself for use withnormal 110 .volt supply, and by slight modification may be used withhigher voltages such as those commonly available in European countries.

More specifically, the invention contemplates improvements in heatingunits of the type wherein a heating coil adjacently encircles a heatresistant electrically non-conductive material such as mica.

BRIEF DESCRIPTION OF THE DRAWING The foregoing and other objects andadvantages will be more apparent from the following detailed descriptionwhen considered in connection with the accompanying drawing wherein:

FIG. 1 is a vertical, sectional view of a heating unit constructed inaccordance with the teachings of the present invention, said unit havingin association therewith a conventional hot water or coffee container;

FIG. 2 is an exploded view of the constituent parts of the heating unitcontemplated by the present invention;

FIG. 3 is an enlarged, horizontal, sectional view taken substantiallyalong the line 3-3 of FIG. 4;

FIG. 4 is a fragmentary, enlarged, vertical sectional view takensubstantially alongthe line 4--4 of FIG. 3; and, p

FIG. 5 is a fragmentary, vertical, transverse sectional view takensubstantially along the line 5-5 of FIG. 3. i

A DESCRIPTION OF A'PREFERRED EMBODIMENT Referring now to the drawingmore in detail, wherein like numerals have been employed to designatesimilar parts throughout the various figures, it will be seen that aheating unit designated generally by the numeral 10, is shown inoperative association with a-stand 12 for supporting a conventionalcoffee container 14. The stand or base 12 is-provided with a well 16 foraccommodating the heating'unit l0.

As will be seen from the exploded illustration in FIG. 2, the heatingunit comprises a metallic hot plate 18, anelectrically insulating sheetor disc 20, a section 22 which includes coplanar sheets of mica 24 and26 having a heating coil 28 adjacently encircling said sheets, a secondelectrically insulating plate or disc 30, a metallic casing disc 32, anda sheet metal ring or collar 32, and is formed with a depending shank 38adapted to accommodate a nut member 40 as shown in FIG. 1. An annularflange 42 of the disc member of the disc member 32 is adapted forclamping engagement with a complementary flange 44 of the ring 34. Afterthe aforesaid constituent parts have been associated in theorderdescribed above, a flange 46 of the hot plate 18 may be bentradially inwardly so as to clamp the flanges 42 and 44 together asclearly shown in FIG. 4.

Particular attention is directed to the shape and disposition of theheat resistant sheet members 24 and 26. The peripheries of these sheets,in the aggregate,

substantially define a circle. Dimetral margins 48 and 50 are adjacentlyspaced from each other as shown in FIGS. 2 and 3. Opposite extremitiesof the coil 28 are suitably connected with the terminal members 52 and54. Sections of the terminal members 52 and 54 extend through openings52a and 54a respectively, in the metallic disc member 32, see FIGS. 2and 5. Suitable insulating cement 56 may be employed to hold theterminals firmly within their respective apertures. Each of theterminals 52 and 54 are electrically coupled with conductors 52b and54b, respectively. Conventional plug and socket means 58 connects withthe aforesaid electrical conductors 52b and 54b.

In instances where desired, the ring member 34 may be dispensed with andthe flange 46 of the plate member 18 may be clamped directly against theflange 42. In such instances the shank member 36 may be dispensed with.Thus, the invention contemplates a heating unit of relatively thincompact form with or without the ring member 34.

From the foregoing it will be apparent that the present inventioncontemplates a very compact heating unit in which heat is uniformlydistributed to the upper plate member. By employing heating coilswrapped around thin heat resistant sheets, such as sheets of mica, theperipheries of which in the aggregate substantially define a circle,heat will be uniformly and efficiently distributed to the disc-like hotplate. Also by crimping the margin of the hotplate, either directlyagainst the flange 42, or alternatively against the flange 44, theelectrical heating elements are sealed in position thereby precludingthe association therewith of moisture which might cause shortcircuiting. The number of coil convolutions will be determined by theavailable voltage. Thus if the heating unit is to be used in the UnitedStates, spacing of the coil convolutions would be such as to enable theunit to be used with a volt source, whereas if the unit is to be used inother countries, as for example Europe, a larger number of coilconvolutions would be employed to accommodate a 220 volt source. Theheating unit contemplated by the present invention may be produced veryeconomically. The compactness and simplicity of construction renders theheating unit useable in a wide range of applications and the unit is byno means limited for use as a heater for coffee containers.

I claim:

1. An electrical heating unit including thin coplanar sheets ofheat-resistant, electrically nonconductive material such as mica, theouter peripheries of which in the aggregate generally define an arcuatecontour, said plate adjacently underlying-saidv co-planar sheets, anannularly disposed mounting member for said unit depending from saidsecond plate and provided with flange means clampingly impinged by theouter margin of said first plate.

1. An electrical heating unit including thin coplanar sheets ofheat-resistant, electrically nonconductive material such as mica, theouter peripheries of which in the aggregate generally define an arcuatecontour, said sheets having adjacently spaced diametral margins, anelectrical conductor coil adjacently encircling said sheets, a terminalmember connected with each extremity of said coil, heat resistant andelectrically nonconductive insulating material adjacently superimposingopposite sides of said sheets, a heat conducting plate superimposing theco-planar sheets, a second plate adjacently underlying said coplanarsheets, an annularly disposed mounting member for said unit dependingfrom said second plate and provided with flange means clampinglyimpinged by the outer margin of said first plate.